Topic Contents

Cardiac Perfusion Scan

Test Overview

A cardiac perfusion scan measures the amount of blood in your heart
muscle at rest and during exercise. It is often done to find out what may be
causing chest pain. It may be done after a
heart attack to see if areas of the heart are not
getting enough blood or to find out how much heart muscle has been damaged from
the heart attack.

During the scan, a camera takes pictures of the heart after a
special test medicine (radioactive tracer) is injected into a
vein in the arm. The tracer travels through the blood and into the heart
muscle. As the tracer moves through the heart muscle, areas that have good
blood flow absorb the tracer. Areas that do not absorb tracer may not be
getting enough blood or may have been damaged by a heart attack.

Two sets of pictures may be made during a cardiac perfusion scan.
One set is taken while you are resting. Another set is taken after your heart
has been stressed, either by exercise or after you have been given a medicine.
The resting pictures are then compared with the stress images.

This test is also known by other names including myocardial perfusion scan, myocardial perfusion imaging, thallium scan, sestamibi cardiac scan, and nuclear stress test.

Why It Is Done

A cardiac perfusion scan is done to:

Find the cause of unexplained chest pain or
chest pain brought on by exercise.

Check to see that the heart is getting enough blood after heart
surgery or angioplasty.

Identify a
congenital heart defect and determine how serious it
is. These scans may also be done following surgery to correct a congenital
heart defect.

How To Prepare

Before a cardiac perfusion, tell your doctor if you:

Are taking any medicines, including
erection-enhancing medicines (such as Cialis, Levitra, or Viagra). You may need
to take nitroglycerin during this test, which can cause a serious reaction if
you have taken an erection-enhancing medicine within the previous 48 hours. Ask
your doctor whether you need to stop taking any of your other medicines before
the test.

Are allergic to any medicines or
anesthetics.

Are or might be pregnant.

Are
breast-feeding. Use formula and throw out your breast milk for 1 to 2 days
after the scan.

Do not eat or drink for at least 3 hours before a cardiac perfusion
scan. If you are having a stress scan, avoid alcohol, tobacco, caffeinated
beverages, and nonprescription medicines for at least 24 hours before the test.

Wear comfortable shoes and loose shorts or pants suitable for
exercise. Remove all jewelry before the test.

Talk to your doctor about any concerns you have regarding the need
for the test, its risks, how it will be done, or what the results may mean.
To help you understand the importance of this test, fill out the
medical test information form(What is a PDF document?)
.

How It Is Done

A cardiac perfusion scan is usually done in a hospital radiology or
nuclear medicine department, a doctor's office, or at an outpatient clinic. The
test is done by a doctor and technologist trained in
nuclear medicine.

Resting scan

For resting scans, in which you do not exercise, you will be
asked to remove your clothing above the waist, and you will be given a hospital
gown to wear. Four electrodes will be attached to your chest to keep track of
your heartbeats.

For a resting scan, the injection site on your arm will be
cleaned and an elastic band will be placed around your upper arm. Then a small
amount of the radioactive tracer is injected, usually into a vein on the inside
of your elbow.

You will lie on your back on a table with a large camera
positioned above your chest. The camera records the tracer's signals as it
moves through your blood. The camera does not produce any radiation, so you are
not exposed to any additional radiation while the scan is being done.

You will be asked to remain very still during each scan, which
takes 5 to 10 minutes. The camera will move to take more pictures at different
angles. Several scans will be taken.

The entire test takes 30 to 40 minutes, after which you can
resume your normal activities.

Stress scan using medicine

The stress scan is done in two parts. In many hospitals, the
first images are taken while the person is at rest. Then a second set of images
is taken immediately after the person is given a medicine such as adenosine,
which makes the heart respond like it would to exercise. A stress test with
medicine is usually used when a person cannot exercise for some reason.

For this test, you will be asked to sit or lie on the examining
table and you will be given a routine electrocardiogram (EKG or ECG), which takes
about 5 to 10 minutes.

Then the medicine is injected into your arm. You may get a
headache and feel dizzy, flushed, and nauseated from the medicine, but these
symptoms usually do not last long. Additional EKGs and blood pressure
measurements are often taken. After the medicine takes effect (about 4
minutes), a small amount of radioactive tracer is injected. You will lie down
on a table for a set of scans. The camera records the tracer's signals as it
moves through your blood. The camera does not produce any radiation, so you are
not exposed to any additional radiation while the scan is being done.

Sometimes more pictures are taken after you rest for 2 to 4
hours. You may resume your normal diet and activities after the final set of
scans.

Stress scan using exercise

For stress scans using exercise, your heart rate will be checked
with an
electrocardiogram (EKG or ECG). Because EKG electrodes need
to be attached to the chest to check the heart, men are usually bare-chested
and women usually wear a bra, gown, or loose shirt. For more information, see
the medical test
Electrocardiogram.

The exercise stress scan is done in two parts. First a set of
resting images is taken, then a set of stress images is taken immediately after
exercise. In many hospitals, first resting pictures are taken using one type of
tracer. More pictures are taken using a different tracer after your heart has
been stressed by exercise.

In this stress test, you exercise on a treadmill or stationary
bike. Your heart rate will be checked during the test with standard
electrocardiography. Your blood pressure is checked using a blood pressure cuff
placed on your arm. For more information, see the medical tests
Exercise Electrocardiogram and
Electrocardiogram.

You will begin by walking or pedaling slowly and easily. Every
few minutes, the speed or incline of the treadmill or resistance of the bike
may be increased. You will exercise until you need to stop or until you reach a
suitable heart rate. At that point, a different tracer medicine is injected.
You will probably continue to exercise for an additional 30 to 60 seconds to
circulate the radioactive tracer.

You will then lie down on a table for scanning. Each scan takes 5
to 10 minutes. The camera does not produce any radiation, so you are not
exposed to any additional radiation while the scan is being done.

Sometimes more pictures are taken after you rest for 30 minutes
to 4 hours. You may usually resume your normal diet and activities after the
final set of scans.

In some hospitals, a second injection of radioactive tracer is
repeated several hours after exercise and before the final image. You may be
asked to return 24 hours after the test to have another set of pictures
taken.

How It Feels

The cardiac scanning test itself is painless.

You may feel a brief stinging or burning
sensation when the needle is inserted into the vein in your
arm.

You may be uncomfortable lying still for an extended period of
time on the table during the scans.

If medicine to stress your
heart is used, you may have symptoms of mild nausea, headache, dizziness,
flushing, or chest pain (angina). These symptoms only last a few
minutes.

If you are asked to exercise, you may have chest pain,
breathlessness, lightheadedness, aching in your leg muscles, and fatigue.
Report these to the technician. If the symptoms are severe, the exercise part
of the test may be stopped.

Risks

Cardiac perfusion scans are usually safe. There is always a slight
chance of damage to cells or tissue from radiation, including the low levels of
radiation used for this test. But the chance of damage from the radiation is
usually very low compared with the benefits of the test.

The risk of exercise depends on the condition of your heart and
your general level of health. The risks include:

Fainting.

Chest
pain.

An irregular heartbeat.

Heart attack.
There is a slight risk that death may result if a heart attack occurs during
the test.

After the test

Call 911 or other emergency
services immediately if you develop:

Chest pain.

Trouble breathing.

Results

A cardiac perfusion scan measures the amount of blood in your heart
muscle at rest and during exercise. Test results are usually available within 1
to 3 days.

Cardiac perfusion scan

Normal:

The radioactive tracer is evenly distributed throughout
your heart muscle.

No areas of abnormal tracer absorption are
present.

Abnormal:

Some areas of heart muscle are not getting enough blood
(ischemia). This may mean that the heart has been damaged or that coronary artery
disease is present.

The heart is enlarged and the left pumping chamber
(ventricle) is not working well.

What Affects the Test

Reasons you may not be able to have the test or why the results may
not be helpful include:

A cardiac perfusion
scan is a less invasive method than cardiac catheterization and angiography for
determining whether a person with moderate risk of coronary artery disease
(CAD) has the disease. For more information, see the medical tests
Angiogram and
Cardiac Catheterization.

Cardiac perfusion
scans cannot distinguish an area of old injury (scar tissue) from a newer
injury caused by a recent heart attack.

A normal result can help
reassure a person with unexplained chest pain and an abnormal stress
electrocardiogram that there is not significant
coronary artery disease.

A few small areas of abnormal tracer
absorption may mean that only small areas of the heart muscle are not getting
enough blood flow. In this case, treatment with medicine may be an
option.

A cardiac perfusion scan is often the first test done in
younger women (when the cause of chest pain is uncertain) after the medical
history and physical examination. This is because a simple stress
electrocardiogram is less accurate in younger women.

Some
cardiologists believe that a stress echocardiogram
provides information similar to a cardiac perfusion scan. But a cardiac
perfusion scan may provide better information than a stress echocardiogram
about blood flow to the heart muscle. For more information, see the medical
test
Echocardiogram.

Klocke FJ, et al. (2003). ACC/AHA/ASNC guidelines for
the clinical use of cardiac radionuclide imaging—Executive summary. A report of
the American College of Cardiology/American Heart Association Task Force on
Practice Guidelines. Circulation, 108(11): 1404–1418.
Available online:
http://circ.ahajournals.org/content/vol108/issue11/index.shtml.

related physicians

related services

This information does not replace the advice of a doctor. Healthwise disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use.
Privacy Policy.
How this information was developed to help you make better health decisions.